diff --git a/src/glsl/glcpp/glcpp-lex.l b/src/glsl/glcpp/glcpp-lex.l
index 2cfe203dacf..2b92fd37e2b 100644
--- a/src/glsl/glcpp/glcpp-lex.l
+++ b/src/glsl/glcpp/glcpp-lex.l
@@ -250,7 +250,7 @@ HEXADECIMAL_INTEGER	0[xX][0-9a-fA-F]+[uU]?
 	}
 
 	/* Single-line comments */
-<INITIAL,DEFINE>"//"[^\r\n]* {
+<INITIAL,DEFINE,HASH>"//"[^\r\n]* {
 }
 
 	/* Multi-line comments */